The present invention relates to systems and methods for removing radioactive and/or hazardous materials from steel, concrete, or other solid surfaces and thereafter treating the generated waste to render a significant portion thereof essentially free of contaminants, and disposing of the reduced volume of contaminated waste. More specifically, the invention relates to systems and methods wherein a pressurized mixture of sodium bicarbonate and air is ejected from a nozzle and directed in a concentrated spray upon a contaminated surface, with water being added at the nozzle during blasting as required to control dust. Water is added after the blasting to dissolve the spent sodium bicarbonate, and the waste material is treated to remove a significant portion of the contaminated solids, the resulting liquid phase being further treated for removal of contaminants to produce an essentially contaminant-free final effluent.
Various surfaces which are contacted by radioactive, toxic and/or other hazardous materials within industrial facilities, and the like, must periodically be decontaminated in order to permit inspection and/or repair, as well as reuse, recycling or sale of the building or equipment incorporating such surfaces. Among the more common procedures employed to effect such decontamination is that of abrasive blasting. Abrasive media used for surface decontamination have included sand, black beauty (coal slag) and steel shot, as well as liquid or solid carbon dioxide. The use of materials which remain in a solid state after impinging upon and removing contaminants from the treated surface requires costly handling and disposal of a large volume of contaminated waste. Media which is in, or converts to, the gaseous state is difficult to contain and decontaminate.
It is a principal object of the present invention to provide a method and system employing a number of otherwise conventional elements of apparatus in novel sequence and combination to effect significant reduction in the volume of contaminated solid waste generated in decontamination of solid surfaces by abrasive blasting.
Another object is to provide a novel and improved method and system of removing radioactive or hazardous material from a solid surface by abrasive blasting which reduces the cost of disposal of contaminated waste.
A further object is to provide a method and system for removal of contaminants from solid surface by abrasive blasting utilizing water soluble, low cost, readily available blasting media, namely, sodium bicarbonate.
Other objects will in part be obvious and will in part appear hereinafter.